[O:1]1[C:5]2[CH:6]=[CH:7][C:8]([CH:10]([S:14]([C:17]3[CH:22]=[CH:21][C:20]([CH3:23])=[CH:19][CH:18]=3)(=[O:16])=[O:15])[NH:11][CH:12]=O)=[CH:9][C:4]=2[O:3][CH2:2]1.P(Cl)(Cl)(Cl)=O.N1C(C)=CC=CC=1C.C(=O)([O-])O.[Na+]>C1COCC1>[N+:11]([CH:10]([S:14]([C:17]1[CH:18]=[CH:19][C:20]([CH3:23])=[CH:21][CH:22]=1)(=[O:16])=[O:15])[C:8]1[CH:7]=[CH:6][C:5]2[O:1][CH2:2][O:3][C:4]=2[CH:9]=1)#[C-:12]To a solution of N-[benzo[1,3]dioxol-5-yl-(toluene-4-sulfonyl)-methyl]-formamide (740 mg, 2.22 mmol) in THF (50 mL) was slowly added phosphorous oxychloride (0.41 mL, 4.44 mmol, 2 equiv). The resulting reaction mixture was stirred at ambient temperature for 2 hours, cooled to 0° C. and slowly treated with 2,6-lutidine (1.55 mL, 13.32 mmol, 6 equiv). The reaction mixture was stirred at ambient temperature for 48 hours, treated with saturated aqueous sodium hydrogen carbonate (80 mL), and then extracted with ethyl acetate (50 mL). The organics were dried over magnesium sulfate and concentrated in vacuo. Silica gel chromatography (20% ethyl acetate in hexane) provided 5-[Isocyano-(toluene4-sulfonyl)-methyl]-benzo[1,3]dioxole as a white solid (200 mg, 29%).
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